Abstract: Dimethylundeca-3,9-dien-2-one was prepared from the starting material citronellal reacting with acetone via aldol condensation, followed by reacting with α-bromoethyl acetate in the presence of Zn through Reformatskii reaction to obtain target chain. After hydrolysis, esterification and etherification, the isomeric products, isopropy-11-methoxy-3,7,11-trimethy1-(2E,4E)-dodecadienoate, which possess juvenile hormone activity, were succeededly synthesized, in which the (2E,4E)-stereoisomer ZR-515, which showed considerably higher activity than other isomers, amounted to 56%. The structures of all compounds in each step were confirmed by 1H NMR、IR and MS.